Safety device for hydraulic brakes



w I 7- Q 76 fl 7 l 20 22 3 39 ll /2 73 a Jan. 12, 1937. L. FONTAINE. JR 2,057,697

SAFETY DEVICE FOR HYDRAULC BRAKES Filed June 25, 1936 Fly. 1.

Fig.4.

Lamar fibula/he Jr:

INVENTOR ATTORNEYS 5 having pistons therein Patented Jan. 12, 1937 PATENT OFFICE SAFETY DEVICE FOR HYDRAULIC BRAKES Lamar Fontaine, Jr.,

of three -eighths to Baton Rouge, La., assignor Kat yn Martin Fontaine,

and one-fourth to'L. J. Voorhies, Sn, both of East Baton Rouge Parish,

Application June '25, 1936, Serial No. 87,313

1 Claim.

This invention relates to safety devices for hydraulic brakes and has for an object to provide auxiliary cylinders between the master cylinder and the wheel cylinders, the auxiliary cylinders respectively adapted to close when pressure is lost in any of. the lines to the wheel cylinders and seal the remainder of with the exception ofthe system pressure tight, the brake having the leak'therein, thus permitting the remaining'brakes to operate properly.

A further object is to provide novel means assembled with the auxiliary cylinder pistons for locking the pistons against returning. to normalposition after having once operated when a leak occurs.

With the above and other objects in view the invention consists of certain novel details of construction and combinations of parts herein after fully described and claimed, it being underto within the scope of the appended claim without departing from the spirit or sacrificing any of the advantages of the invention.

In the accompanyingdrawing forming part of this specification,

Figure 1 is a longitudinal sectional .view through. a safety device for hydraulic brakes con- .structed in accordance with the invention. Figure 2 is a longitudinal sectional view of the device taken ,urel.

Figures is adetail sectional view taken on the line. 33 of Figure 1 and showing one of the auxiliary cylinder pistons locked against returning to normalposition.

Figure 4 is a perspecti spring.

Referring now to thedrawing in which like characters of reference designate similar parts in the various views, l' designates a master cylinder reservoir of a conventional hydraulic brake system, H designates the master cylinder, I2v the master piston, and I3 the helical spring inthe master cylinder ,for returningthe piston to neutral position after each operation. Ports l4 and l5 connect the reservoir with the master cylinder on opposite sides of the master piston when the latter is in neutral position to maintain the cylinder filled with oil which merely forms the fluid pressure medium. These parts are. conventional and the safety devices comprising the subject matter of this invention are" assembled with these" par s as will now be described Preferably two or four auxiliary'cylinders I 6 are formed integral with the master cylinder, two

Y 20 when the latter is in stood that various modifications may vbe resorted in a plane at a right angle to Figv.

shoulder 28 formed at the front end of the cylve view of the locking leaf auxiliary piston will be cates at one end with the, master cylinder through a passage l1 and at the opposite end with a pipe 18 which leads to a corresponding wheel cylinder of the vehicle.

hollow auxiliary piston 20 is slidably fitted in the auxiliary cylinder and houses a helical spring 2|, one end of which bears against the piston and the opposite. end of which is seated in a washer 22. The

The pipe is assembled 'with the auxiliary cylinder by means of a nut I9 .or other suitable connector. A

spring tends to constantly hold the piston in new tral position at the inner end of the cylinder, as shown in Figures 1 and 2. A passage 23 is formed in the master and auxiliary cylinder assembly and connects the master cylinder reservoir I to the auxiliary cylinders iii in neutral position so that the pipe line l8 maybe maintained filled with the pressure fluid medium. r

A leaf spring 25 is fitted in a longitudinal recess 26 formed in the outer surface of the auxiliary piston-at the front end thereof and is anchoredin place by a screw 21. The leaf spring is held seated in the recess by the wall of the auxiliary cylinder but when the piston is moved forward due to loss'of pressure in the pipe I8, the spring is, free to move away from the cylinder at the free end and form a dog to engage against a inderby slidably increasing theinner diameter of the cylinder, and lock the piston against retro-.

forces the master piston forward in the master cylinder ll, to close the .port l5 and force the fluid pressure medium out of the master cylinder through the passage I! into the auxiliary cylinder Hi. Pressure acting. against the auxiliary piston;

20 forces the auxiliary piston forward to seal the advance of the piston passage 23 and force the fluid pressure medium I ahead of it through the sponding wheel cylinder brake.

pipe 18 to the correto set the associated In the event of a leakage in any of the pipe lines- I8. or wheel cylinders, the corresponding sure behind it .and loss of pressure in front 0! it and seal the passage 23, finally coming to rest in forced forward by: pres- 1 operative position against the washer 22,-fixe'd on the pipe line l8 to suitably connect it to the nut l9, as shown in Figure 3. V Thereupon the leaf spring-25 springs outwardly and'lod'ges against the shoulder 28 to prevent retrograde movement of the piston.

As long as there is pressure in the pipe is to the wheel cylinders the auxiliary pistons 20 can move past the passage 23 but not to the washer 22. It moves to about one-half inch from the washer 22 in normal operation. As soon as the pressure in front of the pistons is released by leakage in anypipe it, the corresponding auxiliary piston will immediately be forced against the washer and be locked against retrograde movement. After the brake has beenrepaired the locked auxiliary piston may be restored to normal working order by removing the nut it and inserting a cylindrical shim in the enlarged end of the cylinder to press the spring back into its recess whereupon the piston may be returned to neutral position by sliding it rearward. When the nut i9 is removed the spring 2i is under no pressure.

In a sys em of four auxiliary cylinders there will be alriiauxiliary cylinder for each wheel cylinder, w e a system of two auxiliary cylinders will permit of one cylinder being connected to the wheel cylinders of both front wheels, and the other auxiliary cylinder being connected to the wheel cylinders of both rear wheels. In a system of four cylinders, should leakage occur in any one pipe line, there would still be three remaining brakes functioning properly, while in a system of two auxiliary cylinders should a leakage occur in the pipe line of one of these cylinders, there would be two wheel brakes iunctioning'properly. Three brakes functioning would apply more braking surface and stop the vehicle more quickly, but the vehicle would have a tendency to skid, while if only the front or the rear wheels were 5 braking the ear, the vehicle would have no tendency to skid. r

. From the above description it is thought that the construction and operation of the invention will be fully understood without further explanation.

What is claimed is:

In a hydraulic brake for motor vehicles, a reservoir for a fluid pressure medium, a master cylinder connected with the reservoir, a spring 15 pressed piston in the master cylinder, a plurality of auxiliary cylinders connected with the master cylinder and connected with the reservoir, brake pipes connected with the auxiliary cylinders for conducting the fluid pressure medium to the wheel cylinders of the motor vehicle, spring pressed pistons in the auxiliary cylinders adapted to seal the brake pipes and disconnect the res'er voir from the auxiliary cylinders upon loss of pressure in the brake pipes,fleach auxiliary cylinder having a shoulder in the path of movement of its associated piston, and a spring dog on said associated piston adapted to engage said shoulder and lock the piston stationary in position to seal the brake pipe and cut oil the remrvoir from so the auxiliary cylinder. 

